The present invention relates to a coupling head for a coupling system, in particular for a coupling system for pneumatically connecting a pneumatic brake system of a towing vehicle and a trailer.
A towing vehicle of this type may be, for example, a commercial vehicle such as a truck with a pneumatic brake system.
The prior art has already disclosed coupling systems having coupling heads for pneumatically connecting the brake system of a towing vehicle and a trailer. These systems have a filter unit for filtering the compressed air flowing through the coupling head.
A coupling head of this type is known, for example, from DE 199 31 162 A1 or DE 28 33 834 A1.
DE 10 2009 036 619 A1 discloses, for example, a coupling head for pneumatically connecting the brake system of a towing vehicle and a trailer, in which provision is made of a valve device, which, in the event of a predetermined degree of contamination of the filter unit, controls the latter by means of bypass connections in such a manner that the compressed air flowing through the coupling head no longer flows through the filter of the filter unit, but rather through the bypass connections.
DE 10 2011 002 129 A1 discloses a coupling head having a permanently open bypass which bypasses the filter element. Determined by its design, however, said solution requires a diversion of the compressed air stream, in particular during forward flow bypass operation. A simpler guidance of the flow would be desirable, however.
It is therefore an object of the present invention to develop a coupling head of the type mentioned in the introduction in an advantageous manner, in particular to the effect that an improved flow guidance and emergency function of the coupling head is possible in the case of forward flow and if appropriate also in the case of return flow.
According to the invention, this object is achieved by a coupling head for a coupling system having a coupling head housing, a filter insert and a sealing element, wherein the coupling housing has at least one first coupling connection and at least one second coupling connection, wherein the first coupling connection forms a filter insert recess, into which the filter insert is inserted, and wherein, in the normal operating state, the sealing element bears sealingly against the filter insert, and, in the bypass operating state, opens up a bypass between the sealing element and the filter insert.
The invention is based on the basic concept that, in the bypass operating state, i.e. in a state in which a predetermined degree of contamination of the filter unit is exceeded during forward flow (flow in through the first coupling connection and subsequently through the filter unit), the compressed air supplied flows past the filter insert. Instead, in bypass operation, the intention is for the compressed air to flow along between the sealing element and the outer side of the filter insert. This gives rise to the advantage that the compressed air does not have to flow into the filter insert at all and then diverted from there. Instead, it is sufficient if the air can flow directly past the filter insert through a bypass opening, which may have an annular form, between the sealing element and the filter insert. A diversion of the compressed air stream is therefore no longer necessary. A configuration of this type also makes it possible to reduce the dimensions of the coupling head and in particular the dimensions of the coupling head housing. The sealing element can have a simple design and can be held, for example, in an annular groove in the coupling head housing.
In particular, the coupling head may be a coupling head for a coupling system for pneumatically connecting a pneumatic brake system of a towing vehicle and a trailer.
Furthermore, it can be provided that the sealing element has a radially circumferential sealing lip. This makes it possible to achieve a uniform abutment of the sealing element with its sealing lip against the filter insert. This also leads to secure sealing of the bypass in the normal operating state.
Furthermore, it is possible that, in the mounted state, the sealing lip is positioned against the outer side of the filter insert. In the normal operating state, this achieves secure sealing of the bypass, and therefore the latter is not permanently open.
Moreover, it can be provided that the sealing lip is oriented in the direction of the housing interior of the coupling head housing. This achieves secure and reliable sealing of the bypass both for the normal operating state and for further operating states such as the return flow operation.
Furthermore, it can be provided that the filter insert is fastened separately in the coupling head housing. This allows for fastening independently of the sealing element.
In addition, it is contemplated that the filter insert is fastened by use of a fastener. This makes it possible to achieve simple and reliable fastening of the filter insert in the housing.
By way of example, the fastener may be a screw. The use of screws is cost-effective, because these are standard parts. By way of example, it is contemplated to use self-tapping screws, since these cut their thread itself into the coupling head housing during fitting of the screw.
Furthermore, it can be provided that, in the mounted state, the fastener is arranged on that end of the filter insert which is opposite to the opening of the first coupling connection. This allows for stable fixing and also simple assembly, because it is possible to fit the fastener through the filter insert. The filter insert can be fastened in its filter insert base.
Moreover, it can be provided that, in the mounted state, the fastener is arranged coaxially in relation to the longitudinal axis of the filter insert recess. This allows for the filter insert to be fastened in a centric manner, and this allows for favorable fastening given uniform loading of the filter insert in the coupling head housing.
Furthermore, it is possible that the filter insert has return flow bypass openings, and also a diaphragm, which is arranged in the interior of the filter insert and which closes off the return flow bypass openings sealingly in the normal operating state and, in a return flow bypass state, opens up the return flow bypass openings. This makes it possible to provide an emergency function via a return flow bypass even for return flow operation, i.e. in a case of operation in which air flows outward from the interior of the coupling head through the filter insert in the direction of the first coupling connection. This return flow stream may be the control air flowing into the trailer brake system. Said control air may be returned via the coupling head, and is then discharged, for example, at the trailer control valve of the towing vehicle.
It can be provided that, in the mounted state, the fastener fastens the diaphragm in the filter insert. As a result, both the filter insert and the diaphragm are fastened by way of a single fastener, and this reduces the number of components and facilitates assembly. In principle, other possible fastening methods are also contemplated.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.